Development of the neural correlates of self- and other-referential processing across adolescence.

During adolescence, major changes in brain mechanisms take place and differentiated representations of both the self and of others are developed. Although studies have investigated the neural mechanisms of self- and other-referential processing in adolescents, the development of these mechanisms remain largely unaddressed. Here, we report a three-year longitudinal study with annual measurements, and investigate the developmental trajectories of activity and connectivity underlying self- and other-referential processes in 34 participants from early to mid-adolescence (mean age timepoints 1, 2, 3 = 12.9, 13.9, 15.0 years). Moreover, we probe whether these correlates continue to develop from mid-adolescence to young adulthood by comparing neural correlates of the adolescents at the last measurement to an independent group of 42 young adults (mean age 22 years). Participants underwent functional MRI while performing a trait judgement task in which they indicated whether an adjective described themselves, a similar or a dissimilar peer. Brain activity within the dorsal medial prefrontal cortex (dMPFC) and right temporal parietal junction (TPJ) showed a quadratic change from early to mid-adolescence, with a peak in activity at the second measurement when evaluating the self, the similar and dissimilar peer. No differential activity was observed when comparing the adolescents to young adults. Functional connectivity did not change from early to mid-adolescence, however, connectivity of the dMPFC with a posterior midline region during self- and other-referential processing relative to the control condition reduced from mid-adolescence to young adulthood. Together, these findings provide insight in the developmental trajectories of brain activity and connectivity underlying the development of the self-concept and representations of peers in adolescence.